Re: [PATCH v3 13/25] KVM: TDX: Fold tdx_mem_page_record_premap_cnt() into its sole caller
From: Binbin Wu <hidden>
Date: 2025-10-24 07:38:56
Also in:
kvm, kvm-riscv, kvmarm, linux-coco, linux-mips, linux-riscv, linuxppc-dev, lkml, loongarch
On 10/17/2025 8:32 AM, Sean Christopherson wrote:
Fold tdx_mem_page_record_premap_cnt() into tdx_sept_set_private_spte() as providing a one-off helper for effectively three lines of code is at best a wash, and splitting the code makes the comment for smp_rmb() _extremely_ confusing as the comment talks about reading kvm->arch.pre_fault_allowed before kvm_tdx->state, but the immediately visible code does the exact opposite. Opportunistically rewrite the comments to more explicitly explain who is checking what, as well as _why_ the ordering matters. No functional change intended. Reviewed-by: Rick Edgecombe <rick.p.edgecombe@intel.com> Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Binbin Wu <redacted> One nit below. [...]
+ /* + * If the TD isn't finalized/runnable, then userspace is initializing + * the VM image via KVM_TDX_INIT_MEM_REGION. Increment the number of + * pages that need to be mapped and initialized via TDH.MEM.PAGE.ADD. + * KVM_TDX_FINALIZE_VM checks the counter to ensure all mapped pages
^ Nit: Is pre-mapped better?
+ * have been added to the image, to prevent running the TD with a
+ * valid mapping in the mirror EPT, but not in the S-EPT.
+ */
+ if (unlikely(kvm_tdx->state != TD_STATE_RUNNABLE)) {
+ if (KVM_BUG_ON(kvm->arch.pre_fault_allowed, kvm))
+ return -EIO;
+
+ atomic64_inc(&kvm_tdx->nr_premapped);
+ return 0;
+ }
+
+ return tdx_mem_page_aug(kvm, gfn, level, pfn);
}
static int tdx_sept_link_private_spt(struct kvm *kvm, gfn_t gfn,